Electronic products need to be able to withstand a variety of environments. Conventional waterproofing for a button arranged on a sidewall of an outdoor mobile phone is shown in FIG. 1 and FIG. 2; the waterproof structure includes a casing 100, a button 200, a silicone member 300, and a button switch 400. The casing is a double-color molded product. An outer surface of the casing is provided with a soft rubber layer 101. The material of the button 200 is the same as the material of the soft rubber layer 101. The button 200 and the soft rubber layer 101 are an integrated structure, and the button 200 and the casing 100 are integrated molded, thus the sealing and waterproofing of the button 200 can be assured. The button 200 protrudes out of a surface of the soft rubber layer 101. The protrusion portion of the button 200 is of an arch structure 201. A protruding height that the arch structure 201 protrudes from the soft rubber layer 101 provides a range of elastic travel for the button 200. Considering that the button 200 is prominent on the mobile phone, the protruding height cannot be set to be too high, otherwise the whole appearance of the product will be influenced. The silicone member 300 is assembled to the casing 1. A protrusion 301 is provided on a side of the silicone member 300 facing the button 200. The protrusion 301 contacts the arch structure 201. The silicone member 300 is provided with a convex housing 302 at another side of the silicone member 300 opposite to the protrusion 301. The button switch 400 is assembled and fixed to the casing 1. The button switch 400 faces the convex housing 302, and the button switch 400 and the convex housing 302 press against each other. When the button 200 is pressed, because of the arch structure 201 being made of soft material and a certain elastic travel allowed by the arch shape of the arch structure 201, a deformation is generated when being pressed. The deformation further acts on the silicone member 300, causing the silicone member to generate a displacement at a direction of the pressing, thus the button switch is activated and a corresponding function is triggered. In the aforementioned waterproof structure for a button, because of a limit of the protrusion height that the arch structure 201 protrudes from the soft rubber layer 101, only a small range of elastic travel is provided. Not only does this impart a bad feel when using the button 200, but also the button 200 cannot be activated if the range of elastic travel is not enough. Moreover, because the button 200 and the soft rubber layer 101 are an integrated structure, and the button 200 and the casing 100 are integrally molded, the button 200 needs to be visibly suitable for the soft rubber layer 101 in the material and the color, therefore the color of the outer surface of the product is monotonous, lacking design flexibility.